[all-commits] [llvm/llvm-project] 67e35b: [LV] Check full partial reduction chains in order....

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 67e35bbebbed5e33a173751d019c22e4effa65fd
      https://github.com/llvm/llvm-project/commit/67e35bbebbed5e33a173751d019c22e4effa65fd
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2025-11-20 (Thu, 20 Nov 2025)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/test/Transforms/LoopVectorize/AArch64/partial-reduce-incomplete-chains.ll

  Log Message:
  -----------
  [LV] Check full partial reduction chains in order. (#168036)

https://github.com/llvm/llvm-project/pull/162822 added another
validation step to check if entries in a partial reduction chain have
the same scale factor. But the validation was still dependent on the
order of entries in PartialReductionChains, and would fail to reject
some cases (e.g. if the first first link matched the scale of the second
link, but the second link is invalidated later).

To fix that, group chains by their starting phi nodes, then perform the
validation for each chain, and if it fails, invalidate the whole chain
for the phi.

Fixes https://github.com/llvm/llvm-project/issues/167243.
Fixes https://github.com/llvm/llvm-project/issues/167867.

PR: https://github.com/llvm/llvm-project/pull/168036



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